Luca Bacci authored May 01, 2019 and Mike Fleetwood committed May 05, 2019

Before Gtk 3.22 GtkScrolledWindow propagated natural size to its
Children and so on to descendants.  In Gtk 3.22 this was changed to
always request the minimum size.  This was done because it is believed
to be a safer default (gives a better behaviour) in case of dynamic
content inside the scrolled window, that is, content that may change
allocated size. [1][2][3]

When the scrolled window content is not dynamic the natural size is
preferable because it gives a better looking layout and without any
downside.

In the case of GParted content which is not dynamic, so request the
scrolled windows to allocate children at natural sizes for Gtk >= 3.22.

The benefits of natural size allocation are evident in presence of
wrapping labels (for example inside the "Partition Info" dialog), that
with the minimum size request likely end up taking a very small width.

References:

[1] Gtk commit from 2016-08-31:
    GtkScrolledWindow: Make propagation of natural child sizes optional
    GNOME/gtk@0984d162
    "Making propagation of child natural sizes mandatory (or default,
    even) was evidently a mistake as this causes dynamic content in a
    scrolled window to resize it's parent when the scrolled window is
    competing for space with an adjacent widget."

[2] Gtk 3.22 Reference Documentation -
    gtk_scrolled_window_set_propagate_natural_width
    https://developer.gnome.org/gtk3/3.22/GtkScrolledWindow.html#gtk-scrolled-window-set-propagate-natural-width

[3] Gtkmm 3.24 Gtk::ScrolledWindow Class Reference,
    set_propagate_natural_width() method
    https://developer.gnome.org/gtkmm/3.24/classGtk_1_1ScrolledWindow.html#a2d4cb945688ecb8739efd70b18742779

[4] Gtkmm 3.21.6 NEWS
    https://gitlab.gnome.org/GNOME/gtkmm/blob/3.21.6/NEWS
    "ScrolledWindow: Added get/set_propagate_natural_height/width() and
    the properties."

Closes !39 - Always request natural size inside Gtk::ScrolledWindow